JPS60249064A - Displacement detecting circuit - Google Patents

Abstract

PURPOSE:To make a semiconductor chip small in size, and also to improve the detecting accuracy by combining at a gate circuit an encoded pulse generated by an encoder in accordance with a displacement of a part whose displacement is to be detected, and a clock signal pulse generated by a clock signal generating circuit. CONSTITUTION:A magnetic pole plate 4 on which one or two or more NS magnetic poles are placed is installed to a revolving shaft 2 being a part whose displacement is detected of a rotary base of a tape reel, and an encoder 6 for encoding a rotation of the magnetic pole plate 4 is installed. A clock signal generator 8 which corresponds to the encoder 6 and generates a closk pulse having a higher frequency than its encoded pulse is installed. The encoded pulse of the encoder 6 and the clock pulse of the generator 8 are applied to an AND circuit 10. The clock pulse is applied to a shift register 12 together with a logical output of the circuit 10. The input pulse of a register 12 and the output pulse of FFs 141-14n for constituting the register 12 are supplied to an exclusive OR 16, and a displacement detecting output is fetched. In such a way, the detecting accuracy can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a displacement detection circuit for detecting displacement such as the end of a magnetic tape of a tape recorder or rotation stoppage.

[Conventional technology]

In a tape recorder, the end of recording or playback, or the end of magnetic tape forwarding or rewinding, is determined by detecting the arrival of the end of the magnetic tape. The arrival of the end of the magnetic tape is detected by the rotation of the rotating part stopping. Then, for the detection, a detection element such as a Hall sensor is used, and the detection output is differentiated by a differentiation circuit.
The presence or absence of rotation is determined by the presence or absence of DC output.

Conventionally, the differential circuit installed in such a rotation detection circuit requires a capacitor, and if a detection circuit including such a capacitor is constructed using a semiconductor integrated circuit, the semiconductor chip becomes large, and if the capacitor is Even when connecting to the outside, terminals (pins) for this must be formed on the semiconductor device, which makes the configuration complicated and has drawbacks such as low detection accuracy.

[Problem that the invention seeks to solve]

This invention aims to simplify the configuration by removing the capacitor, reduce the semiconductor chip size when configured with a semiconductor integrated circuit, and improve detection accuracy.

[Means for solving problems]

An encoder that encodes the displacement of the displacement detection section, a clock signal generator that generates a clock pulse with a higher frequency than the pulse frequency of this encoder, an output clock pulse of this clock signal generator, and an output pulse that is generated by the encoder. It consists of a gate circuit that combines these and generates a logical output.

[For production]

By combining the encoded pulses generated by the encoder according to the displacement of the displacement detection part and the clock signal pulses generated by the clock signal generation circuit using a gate circuit,
For example, the presence or absence of displacement is detected by logical product of both.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.

FIG. 1 shows an embodiment of a displacement detection circuit according to the present invention, and this embodiment is constructed as a rotation detection circuit for detecting the end of a magnetic tape of a tape recorder.

In FIG. 1, a magnetic pole plate 4 in which one or more NS magnetic poles are arranged is attached to a rotating part 2 as a displacement detection part of a rotary table of a tape reel, and an encoder that encodes 40 rotations of this magnetic pole plate is attached. 6 is installed.

Corresponding to the encoder 6, a clock signal generator 8 is installed which generates a clock pulse having a higher frequency than the encoded pulse.

The encoded pulse generated by the encoder 6 according to the amount of rotation of the rotating part 2 or its displacement and the clock pulse generated by the clock signal generator 8 are processed as a gate circuit that detects that both pulses are present at the same time. ANI) Circuit 1
added to 0.

The clock pulse and the logical product output of the AND circuit 10 are applied to the shift register 12. This shift register 12 includes a plurality of flip-flop circuits (
(hereinafter referred to as FF circuit) 14I, 14□, 143...
・14. 1 are connected in series.

The input pulse of this shift register 12 and each F, F circuit 141.14□, 14. ...14. The output pulse 1 is applied to the exclusive 0R16, and the displacement detection output is taken out from the output terminal 18.

Based on the above configuration, its operation will be explained with reference to FIG.

In FIG. 2, A is the output of the encoder 6, B is the output clock pulse of the clock signal generator, and C is the output of the encoder 6.
The output of the circuit 10, D, indicates the output pulse of the exclusive 0R16. And the intervals jl, jj and t
, are rotation stop sections, section 1, . 1. is the rotation section,
The encoder 6 generates or stops encoding pulses corresponding to each section, but in the section t1, the encoder 6 generates a low (L) level output in relation to the position of the magnetic pole, and in the section t, the encoder 6 generates a low (L) level output. The relationship is opposite to that, and the encoder 6 generates a high (1()) level output.

The output of the encoder 6 and the clock pulse shown in FIG. 2B are ANDed by an AND circuit IO, and the AND output shown in FIG.

That is, the output pulse of the AND circuit 10 is
4. ．． 14□, 143 . , and the FF circuit 14 are applied to the exclusive 0R16, and as a result, the exclusive 0R
16, as shown in the second diagram, generates a displacement detection output that is at H level during rotation, that is, when a displacement occurs in the displacement detection section, and at L level when there is no displacement. In this case, the displacement detection output is the FF circuit 1 of the shift register 12.
4. ~14I, a delay occurs depending on the number of stages, but depending on the state of the detection output, displacement such as rotation detection can be detected. It can be detected from

Since such a displacement detection circuit does not include a capacitor, when it is constructed using a semiconductor integrated circuit, it is possible to reduce the size of the semiconductor chip and improve detection accuracy.

Although the shift register 12 and the exclusive 0R16 are installed in the embodiment, for example, when detecting the end of the magnetic tape from the rotation of the reel stand of a tape recorder, the reel stand is changed depending on the remaining amount of the magnetic tape. Since the number of rotations increases, the output pulse width of the AND circuit 10 changes accordingly, so it is also possible to detect the rotational state or the stopped state. Therefore, displacement detection is possible even without the shift register 12 and the exclusive 0R16.

Further, in the embodiment, the rotation detection of the reel stand of a tape recorder has been described, but the present invention can also be used to detect displacement other than rotation, and similar effects can be expected.

〔Effect of the invention〕

As explained above, according to the present invention, a circuit can be configured without a capacitor, the circuit configuration can be simplified by reducing the number of parts, and the displacement detection accuracy can be improved. Miniaturization can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the displacement detection circuit of the present invention, and FIG. 2 is an explanatory diagram showing its operating pulses. 2... Rotating unit as a displacement detection unit, 6... Encoder, 8... Clock signal generator, 10... AND circuit as a gate circuit.

Claims (1)

[Claims] An encoder that encodes the displacement of the displacement detection section, a clock signal generator that generates a clock pulse with a higher frequency than the pulse frequency of this encoder, an output clock pulse of this clock signal generator, and an output pulse that is generated by the encoder. A displacement detection circuit consisting of a gate circuit that combines the above and generates a logical output.